Mixtures of gases are frequently used in welding operations, for example, a mixture of gases can be used for shielding purposes during metal inert gas (MIG) welding operations.
Welding gas mixtures are invariably transported in special gas cylinders between a first location at which the cylinders are filled with the various constituents of the gas mixture and a location at which the welding operation is to take place.
In order to maintain a uniform consistency of gas mixture leaving a cylinder during, for example, a welding operation it is necessary that the constituents are thoroughly mixed either when entering or after entry within the interior of the cylinder. In order to provide for adequate gas mixing it is known to roll cylinders or leave them free standing on their sides. However, this known method has disadvantages in that larger cylinders can weigh in the order of 300 lbs which means considerable effort has to be expended to manoeuvre the cylinders to ensure adequate mixing.
To avoid the necessity of rolling heavy cylinders so-called "dip tubes" have been used which depend from the usual gas valve to be found at one end of the cylinder and into the interior of the cylinder. Each tube is sealed at its distal end and spaced holes are provided along its length. These known dip tubes have been used to mix gases in a cylinder with varying degrees of success.
It is an aim of the present invention to provide a gas cylinder which includes a venturi device located within the cylinder which functions to mix two or more constituents of a gas mixture at the time the cylinder is being filled with said constituents.